Tubular ball-mill.



No. 687,5I9. Patented Nov. 26, I901.

M. J. DAVIDSEN.

TUBULAR BALL MILL.

(Application fllqd Nov. 29, 1898.)

(No Model.)

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UNITED STATES PATENT OFFICE.

MEYER JOSEPH DAVIDSEN, OF COPENHAGEN, DENMARK.

TUBULAR BALL-MILL.

SPECIFICATION forming part of Letters Patent No. 687,519, dated November 26, 1901.

' Application filed November 29, 1898. Serial No. 697,757. (No model.)

T0 at whom it may concern:

Be it known that I, MEYER J OSEPH DAVID- sEN, a subject of the King of Denmark, residing at Copenhagen, Denmark, have invented certain new and useful Improvements in Tubular Ball-Mills, of which the following is a specification.

Tubular ball-mills consisting of a drum of tube shape and having a smooth inner surface partitioned off into connecting-compartments, said drum being arranged to revolve on its horizontal axis, are already known. In these mills the drum is partly filled with loose balls and the material to be ground is introduced continuously at the center or near the center at one end of the drum, while the pulverized material or powder leaves the drum continuously at the other end.

The object of the present invention is a tubular ball-mill of the described class, in which the grinding may be effected in less time than heretofore and in which themill may be used for grinding softer material than customary-such as, for instance, coaleven if this material be fed into the mill in large pieces.

A further object is to improve the means for partitioning off the drum.

In the present invention the tubular ballmill consists of a drum, partitions dividing said drum into alternate grinding and conveying chambers, grinding-balls in the chambers, inlet and outlet openings for the con veyingchambers, and suitable valves arranged to close the outlet-openings, as will be hereinafter particularly described and then pointed out in the claims.

In the accompanying drawings, Figure 1 is a longitudinal section of a tubular ball-mill embodying my invention, and Fig. 2 is an enlarged transverse section thereof on line 2 2 of Fig. 1.

The conveying-chambers each consist of an annular space along the periphery of the drum D and formed by vertical transverse partitions 10, this space being, by means of radial partitions p, divided into a number of cells K. Each of these cells communicates with the preceding grinding-chamber A, B, or 0, according to the number of grindingchambers employed, through side inlet-openings c, and with the next-following grindingchamber through the openings 0 in the inner wall of each cell, which openings 0 are preferably closed by means of ball-valves '0.

The material to be ground is introduced continuously through the hollow bearing e for the inlet end of the drum into the grinding-chamber A, which is about half filled with loose balls. The material will then accumulate inside the grinding-chamber near the inlet and from this point will constantly slide down through the part of the chamber filled with balls and will assume an inclined position, the principal height of which is equal to the radius of the grinding-chamber, while its length is equal to the length of the said chamber.

As soon as the material to be ground has reached the conveying-chamber it will enter the lower cells K through the inlet-openings c. As the drum is revolved, however, the material that has entered these cells K will be carried upwardly by means of the radial partitions 19' until it can escape through the openings 0 and fall into the next grindingchamber B.

Openings 0 of the lowermost cells will be blocked or closed by means of the ball-valves o, and the material will thereby be prevented from falling or entering into the lower cells and be thence conveyed again into the preceding grinding-chamber A. The ball-valves o will move away from their seats in the uppermost cells, thus allowing the material to fall into the grinding-chamber B. The same action takes place between grinding-chambers B G. The movement of the ball-valves o is'limited by means of stops or cross-bars s,

fixed to the adjacent walls of the partitions p.

After entering the grinding-chamber C the finished material may leave the mill either through a series of openings 72. in a plate H at the outlet end of the drum and openings h at the sides and thence through the outlet t', or, if preferred, the ground material may be carried through the last conveying-chamber in such a manner as thatit will directly leave the drum at its center. The balls in the various grinding-chambers may be of different relative sizes, in which case it is preferable to use balls of gradually-decreasing diameter as the material gets finer. The number of the chambers, as well as themanner in which the drum is caused to revolve and other details, may be varied according to circumstances.

What I claim is 1. Atubularball-mill, consisting of a drum, partitions arranged in pairs and dividing said drum into alternate grinding and conveying chambers, grindingballs in the grindingchambers, inlet and outlet Openings for the conveying-chambers, and valves arranged to close the outlet-openings, substantially as set forth.

2. Atubularball-mill, consisting of adrum,

vertical partitions arranged in pairs and dividing said drum into alternate grinding and conveying chambers, grinding-balls in the 

